But shouldn't I be able to open Word (doc) documents and PDFs stored on my server? The program tells me that it can't find a file viewer. This isn't right in my opinion as I have the attachment service installed on my device. It works with text files and images but not with docs and PDFs (which would be extremely valuable to me as my BB doesn't have a MediaCard slot).

Does anyone have the same issue?

The BlackBerry device does not support opening Word or PDF files natively on the device yet. The attachment service on your BlackBerry basically transforms the files to a compressed format that is understood by your device before it arrives to the device. The reason for this is so that you can view an attached PDF that might be a couple of megs without download a massive document to your device over an expensive and slow data connection.

Stay tuned as I heard that BlackBerry devices in the future will be able to handle the actual native document formats on the device, using other applications like Dataviz, Repligo and eOffice.